Structure, Resolution, and Racemization of Decakis(dichloromethyl)biphenyl

Silvio E. Biali, Bart Kahr, Kurt Mislow, Yoshio Okamoto, Ryo Aburatani

Research output: Contribution to journalArticle

Abstract

Decalds(dichloromethyl)biphenyl (1) was obtained by photochlorination of decamethylbiphenyl. Crystals of the 1:1 THF solvate are monoclinic, space group P21/n, a = 17.296 (5) Å, b = 10.091 (3) Å, c = 21.731 (5) Å, 8 = 96.79 (2)°, Z = 4. The disposition of the dichloromethyl groups on both rings is all-geared, and the molecule has approximate C2 symmetry. The 1H NMR solution spectrum of 1 is consistent with a time-averaged C2 conformation. The molecule assumes a curved shape that is well reproduced by empirical force field calculations. Homo- and heterodirectional relationships between subcycles of the molecular model are discussed. Enantiomers of 1 were separated by HPLC on a column of cellulose tris(3,5-dimethylphenylcarbamate). The biphenyl racemizes with a barrier (ΔG) of 23.7 kcal mol−1; the threshold mechanism for the enantiomerization most likely involves internal rotation of the dichloromethyl groups rather than rotation of the pentakis-(dichloromethyl)phenyl groups about the central biphenyl bond.

Original languageEnglish (US)
Pages (from-to)1917-1922
Number of pages6
JournalJournal of the American Chemical Society
Volume110
Issue number6
DOIs
StatePublished - Mar 1 1988

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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